Rotor assembly and motor using same

Abstract

A rotor assembly for a motor is disclosed. The motor has a minimum air gap width value. The rotor assembly includes magnets, a main-body portion, magnet-receiving slots and arc-trimming portions. Each of the magnet-receiving slots is disposed around a central axis of the main-body portion and locates through the main-body portion for accommodating the corresponding magnet therein. The magnet-receiving slot has a slot width value. The arc-trimming portions spatially correspond to the magnet-receiving slots. Each of the arc-trimming portions and a geometric symmetry center of the corresponding magnet-receiving slot together form an arc-trimming depth value. The arc-trimming depth value is greater than a sum value of a rate constant multiplied by the slot width value and then subtracted 2 times of the minimum air gap width value, and is less than the sum value of the rate constant multiplied by the slot width value and then plus 2 times of the minimum air gap width value.

What is claimed is: 
     
       1. A rotor assembly for a motor, wherein the rotor assembly is matched with a stator assembly, the rotor assembly and the stator assembly have a minimum air gap width value therebetween, and the rotor assembly comprises:
 a plurality of magnets; 
 a main-body portion having a center axis and an outer peripheral edge; 
 a plurality of magnet-receiving slots spatially corresponding to the plurality of magnets and accommodating the plurality of magnets therein, wherein the plurality of magnet-receiving slots are disposed on the main-body portion around the central axis of the main-body portion and located through the main-body portion, wherein each of the plurality of magnet-receiving slots accommodates the corresponding magnet therein, the magnet-receiving slot has a slot width value in an outward direction extending from the central axis; and 
 a plurality of arc-trimming portions adjacent to the outer peripheral edge and spatially corresponding to the plurality of magnet-receiving slots, wherein each of the plurality of arc-trimming portions and a geometric symmetry center of the corresponding magnet-receiving slot together form an arc-trimming depth value, and an arc-trimming interval value is formed between the arc-trimming portion and an end of the corresponding magnet-receiving slot, wherein the arc-trimming depth value is greater than a sum value of a rate constant multiplied by the slot width value and then subtracted 2 times of the minimum air gap width value, and is less than the sum value of the rate constant multiplied by the slot width value and then plus 2 times of the minimum air gap width value, wherein the arc-trimming interval value is greater than 0.5 times of the minimum air gap width value and is less than 2 times of the minimum air gap width value. 
 
     
     
       2. The rotor assembly according to  claim 1 , wherein the rotor assembly has a rotor outer diameter length and the stator assembly has a stator outer diameter length, wherein a ratio of the rotor outer diameter length to the stator outer diameter length is ranged from 60% to 70%. 
     
     
       3. The rotor assembly according to  claim 1 , wherein the rate constant is greater than 0 and is less than 0.25. 
     
     
       4. The rotor assembly according to  claim 1 , wherein each of the plurality of magnet-receiving slots comprises two extending slots disposed on two opposite ends of the corresponding magnet-receiving slot, respectively, and in communication with the corresponding magnet-receiving slot. 
     
     
       5. The rotor assembly according to  claim 4 , wherein the extending slot and the corresponding magnet-receiving slot have a communication length, and the communication length is ranged from 0.6 times of the slot width value to 0.8 times of the slot width value. 
     
     
       6. The rotor assembly according to  claim 4 , wherein each of the plurality of arc-trimming portions comprises two extending portions disposed on two opposite ends of the corresponding arc-trimming portion, wherein each of the extending portions extends along the outer peripheral edge, and spatially corresponds to each of the corresponding extending slots, respectively. 
     
     
       7. The rotor assembly according to  claim 6 , wherein the extending slot has an inner edge at least partially parallel to the corresponding extending portion. 
     
     
       8. The rotor assembly according to  claim 7 , wherein the inner edge of the extending slot and the corresponding magnet received within the corresponding magnet-receiving slot have an interval width value, wherein the interval width value is ranged from 0.3 times of the slot width value to 0.5 times of the slot width value. 
     
     
       9. The rotor assembly according to  claim 1 , wherein each two of adjacent arc-trimming portions have a recess portion, and a maximum air gap width value is formed between the recess portion and the stator assembly, wherein the maximum air gap width value is ranged from 3 times of the minimum air gap width value to 5 times of the minimum air gap width value. 
     
     
       10. The rotor assembly according to  claim 1 , wherein the number of the plurality of magnet-receiving slots and the number of the plurality of magnets are 2N, wherein N is an integer, and N is greater than or equal to 2. 
     
     
       11. A motor comprising:
 a stator assembly comprising a hollow portion; and 
 a rotor assembly disposed within the hollow portion and matched with the stator assembly, wherein the rotor assembly and the stator assembly have a minimum air gap width value therebetween, and the rotor assembly comprises:
 a plurality of magnets; 
 a main-body portion having a center axis and an outer peripheral edge; 
 a plurality of magnet-receiving slots spatially corresponding to the plurality of magnets and accommodating the plurality of magnets therein, wherein the plurality of magnet-receiving slots are disposed on the main-body portion around the central axis of the main-body portion and located through the main-body portion, wherein each of the plurality of magnet-receiving slots accommodates the corresponding magnet therein, the magnet-receiving slot has a slot width value in an outward direction extending from the central axis; and 
 a plurality of arc-trimming portions adjacent to the outer peripheral edge and spatially corresponding to the plurality of magnet-receiving slots, wherein each of the plurality of arc-trimming portions and a geometric symmetry center of the corresponding magnet-receiving slot together form an arc-trimming depth value, and an arc-trimming interval value is formed between the arc-trimming portion and an end of the corresponding magnet-receiving slot, wherein the arc-trimming depth value is greater than a sum value of a rate constant multiplied by the slot width value and then subtracted 2 times of the minimum air gap width value, and is less than the sum value of the rate constant multiplied by the slot width value and then plus 2 times of the minimum air gap width value, wherein the arc-trimming interval value is greater than 0.5 times of the minimum air gap width value and is less than 2 times of the minimum air gap width value. 
 
 
     
     
       12. The motor according to  claim 11 , wherein the rotor assembly has a rotor outer diameter length and the stator assembly has a stator outer diameter length, wherein a ratio of the rotor outer diameter length to the stator outer diameter length is ranged from 60% to 70%. 
     
     
       13. The motor according to  claim 11 , wherein the rate constant is greater than 0 and is less than 0.25. 
     
     
       14. The motor according to  claim 11 , wherein each of the plurality of magnet-receiving slots comprises two extending slots disposed on two opposite ends of the corresponding magnet-receiving slot, respectively, and in communication with the corresponding magnet-receiving slot. 
     
     
       15. The motor according to  claim 14 , wherein the extending slot and the corresponding magnet-receiving slot have a communication length, and the communication length is ranged from 0.6 times of the slot width value to 0.8 times of the slot width value. 
     
     
       16. The motor according to  claim 14 , wherein each of the plurality of arc-trimming portions comprises two extending portions disposed on two opposite ends of the corresponding arc-trimming portion, wherein each of the extending portions extends along the outer peripheral edge, and spatially corresponds to each of the corresponding extending slots, respectively. 
     
     
       17. The motor according to  claim 16 , wherein the extending slot has an inner edge at least partially parallel to the corresponding extending portion. 
     
     
       18. The motor according to  claim 17 , wherein the inner edge of the extending slot and the corresponding magnet received within the corresponding magnet-receiving slot have an interval width value, wherein the interval width value is ranged from 0.3 times of the slot width value to 0.5 times of the slot width value. 
     
     
       19. The motor according to  claim 11 , wherein each two of adjacent arc-trimming portions have a recess portion, and a maximum air gap width value is formed between the recess portion and the stator assembly, wherein the maximum air gap width value is ranged from 3 times of the minimum air gap width value to 5 times of the minimum air gap width value. 
     
     
       20. The motor according to  claim 11 , wherein the number of the plurality of magnet-receiving slots and the number of the plurality of magnets are 2N, wherein N is an integer, and N is greater than or equal to 2.